In the manufacture of printed circuit boards for use with small computers or other electronic equipment, it is common to test the circuit board prior to shipment. A common technique for testing a printed circuit board is to install it in a target piece of equipment, such as a small computer, and to run a diagnostic program in that computer.
This technique is time consuming because the equipment must be turned off during installation or removal of the printed circuit board. The requirement for turning off the circuit board arises from the necessity for maintaining the integrity of the circuit board by providing the various bus signals in the proper sequence. For example, it is generally desired to provide power to the circuit board prior to connecting data or control circuits. Similarly, the data and control circuits should be opened prior to turning off the power.
Devices for use in testing circuits are known in the patent literature. For example, U.S. Pat. Nos. 3,904,861 (McNamara) and 4,230,986 (Deaver) show extension boards for use in testing a printed circuit. The extension boards plug into a computer, and the circuit board being tested is attached to the extension board. Other testing devices are shown in U.S. Pat. Nos, 3,676,777 (Charters); 4,152,644 (Lockhart, Jr.); and 4,504,783 (Zasio).